Document no-panic behavior

Author: dflemstr

README.md

@@ -1,7 +1,7 @@
 # femtopb
 
-A tiny footprint, `#[no_std]`, no-alloc Protobuf serialization library.  This allows you to communicate using Protobuf
-on constrained platforms, like bare-metal MCUs with very limited RAM.
+A tiny footprint, `#[no_std]`, no-alloc, no-panic Protobuf serialization library.  This allows you to communicate using
+Protobuf on constrained platforms, like bare-metal MCUs with very limited RAM.
 
 Yes, you heard it right: this library lets you serialize and deserialize Protobuf messages without any dynamic
 memory/heap allocation.
@@ -10,6 +10,11 @@ The library takes care of using simple types with limited use of generics when p
 code size explosion.  The runtime also consists of many tiny functions so that the ones that aren't used can get
 optimized away.
 
+During testing of this crate, checks are made to ensure that `femtopb` code cannot panic.  If  you want to leverage the
+no-panic checks yourself to debug your own project, enable the `assert-no-panic` crate feature.  It is not necessarily a
+good idea to enable this feature for your release code, as enabling this feature might change the generated code
+slightly.
+
 There are some limitations, however.  Messages must be deserialized from continuous `&[u8]` slices, so incremental
 deserialization from other `bytes::Buf` types or streams/files/sockets/... is not supported.  Also, messages borrow
 their source slice for the duration of their lifetime.  Deserialization of repeated fields happens lazily to avoid

src/lib.rs

@@ -1,8 +1,9 @@
 #![cfg_attr(not(test), no_std)]
 //! # `femtopb`
 //!
-//! A tiny footprint, `#[no_std]`, no-`alloc` Protobuf serialization library.  This allows you to
-//! communicate using Protobuf on constrained platforms, like bare-metal MCUs with very limited RAM.
+//! A tiny footprint, `#[no_std]`, no-`alloc`, no-panic Protobuf serialization library.  This allows
+//! you to communicate using Protobuf on constrained platforms, like bare-metal MCUs with very
+//! limited RAM.
 //!
 //! Yes, you heard it right: this library lets you serialize and deserialize Protobuf messages
 //! without any dynamic memory/heap allocation.
@@ -11,6 +12,11 @@
 //! avoid monomorphization code size explosion.  The runtime also consists of many tiny functions
 //! so that the ones that aren't used can get optimized away.
 //!
+//! During testing of this crate, checks are made to ensure that `femtopb` code cannot panic.  If
+//! you want to leverage the no-panic checks yourself to debug your own project, enable the
+//! `assert-no-panic` crate feature.  It is not necessarily a good idea to enable this feature for
+//! your release code, as enabling this feature might change the generated code slightly.
+//!
 //! ## Defining message types
 //!
 //! `femtopb` enables encoding and decoding of messages by deriving the `femtopb::Message` trait.